One of the difficulties which is encountered in the milking of dairy cows is difficulty of accurately sensing when a machine should be removed from a cow. It has been found that timers are unsatisfactory since a cow might vary from day to day, and the period of time required to finish milking different cows varies widely within a single herd.
Efforts have been made to automatically release the teats of a claw from a cow upon termination of milking, and while these efforts have been successful as far as mechanical removal of the claw is concerned, they have not been completely successful as far as sensing the termination of milking cycle is concerned. For example if a milk flow sensor device is used, unless it is of a very elaborate and expensive electronic type, it is liable to contamination and requires tedious cleaning operations. Furthermore it is subject to failure under certain conditions.
The main object of this invention is to provide milking termination means which is pressure controlled, that is, which responds to the slight decrease in pressure (that is, increase in vacuum) which occurs at the end of milking.